TNF Drives Aberrant BMP Signaling to Induce Endothelial and Mesenchymal Dysregulation in a Transgenic Model of Pulmonary Hypertension
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ABSTRACT: The pathobiology of pulmonary hypertension (PH) is complex and multiple cell types (endothelial, smooth muscle, fibroblast, pericyte) contribute to disease pathogenesis. However, the specific molecular crosstalk between endothelial and mesenchymal cells to promote PH is poorly characterized. We previously demonstrated that tumor necrosis factor alpha transgenic (TNF-Tg) mice have a severe PH phenotype.
Project description:We investigate the MED1/KLF4 co-regulation of the BMP/TGF-beta axes in endothelium by studying the epigenetic regulation of BMP receptor type II (BMPR2), ETS-related gene (ERG), and TGF-beta receptor 2 (TGFBR2) and their involvement in the PH. High throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, KLF4 ATAC-seq, and high-throughput chromosome conformation capture (HiC) together with in silico computations were used to explore the epigenetic and transcriptional regulation of BMPR2, ERG, and TGFBR2 by MED1 and KLF4. In vitro experiments with cultured pulmonary arterial endothelial cells (PAECs) and bulk assays were used to validate results from these in silico analyses. Lung tissue from patients with idiopathic pulmonary arterial hypertension (IPAH), animals with experimental PH, and mice with endothelial ablation of MED1 (EC-MED1-/-) were used to study the PH-protective effect of MED1. Levels of MED1 were decreased in lung tissue or PAECs from IPAH patients and rodent PH models. Mechanistically, MED1 acted synergistically with KLF4 to transactivate BMPR2, ERG, and TGFBR2 via chromatin remodeling and enhancer-promoter interactions. EC-MED1-/- mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents. A homeostatic regulation of BMPR2, ERG, and TGFBR2 in ECs by MED1 synergistic with KLF4 is essential for the normal function of the pulmonary endothelium. Dysregulation of MED1 and the resulting impairment of the BMP/TGF- signaling is implicated in the disease progression of PAH in humans and PH in rodent models.
Project description:FUNDC1 protein levels were reduced in PH lung vessels from clinical subjects and animal models. Global Fundc1 deficiency exacerbated PH, while its overexpression is protective. The effect of FUNDC1 was mediated by endothelial cells rather than smooth muscle cells. Further, inducible loss of endothelial Fundc1 in postnatal mice was sufficient to cause PH spontaneously, whereas augmenting endothelial Fundc1 protected against PH before and after the onset of disease. Mechanistically, Fundc1 deficiency impaired basal mitophagy in endothelial cells, leading to accumulation of dysfunctional mitochondria, metabolic reprogramming towards aerobic glycolysis, pseudohypoxia and senescence, likely via a mtROS-HIF2α signaling pathway. Subsequently, Fundc1-deficient endothelial cells increased IGFBP2 secretion that drove pulmonary arterial remodeling to instigate PH. Finally, proof-of-principle in vivo studies showed significant efficacy on PH amelioration by targeting endothelial mitophagy, pseudohypoxia, senescence or IGFBP2.
Project description:TNF Drives Aberrant BMP Signaling to Induce Endothelial and Mesenchymal Dysregulation in a Transgenic Model of Pulmonary Hypertension
Project description:Pulmonary hypertension (PH) is a common complication of systemic sclerosis (SSc) and a leading cause of mortality among patients with this disease. PH can also occur as an idiopathic condition (idiopathic pulmonary arterial hypertension, iPAH). We sought to investigate the transcriptomic alterations in PH vascular populations to understand cellular mechanisms underlying pathobiology of systemic sclerosis associated and idiopathic pulmonary hypertension.
Project description:FUNDC1 protein levels were reduced in PH lung vessels from clinical subjects and animal models. Global Fundc1 deficiency exacerbated PH, while its overexpression is protective. The effect of FUNDC1 was mediated by endothelial cells rather than smooth muscle cells. Further, inducible loss of endothelial Fundc1 in postnatal mice was sufficient to cause PH spontaneously, whereas augmenting endothelial Fundc1 protected against PH before and after the onset of disease. Mechanistically, Fundc1 deficiency impaired basal mitophagy in endothelial cells, leading to accumulation of dysfunctional mitochondria, metabolic reprogramming towards aerobic glycolysis, pseudohypoxia and senescence, likely via a mtROS-HIF2α signaling pathway. Subsequently, Fundc1-deficient endothelial cells increased IGFBP2 secretion that drove pulmonary arterial remodeling to instigate PH. Finally, proof-of-principle in vivo studies showed significant efficacy on PH amelioration by targeting endothelial mitophagy, pseudohypoxia, senescence or IGFBP2. We then performed gene expression profiling analysis using data obtained from RNA-seq of 2 different cells .
Project description:Right heart failure results from advanced pulmonary hypertension (PH) and has a poor prognosis. There are few available treatments for right heart failure. Pulmonary artery remodeling, including changes in pulmonary artery endothelial cells to endothelial-mesenchymal cells, and aberrant fibroblast and pulmonary artery smooth muscle cell (PASMC) proliferation, are characteristics of the pathophysiological process of PH. As a result, the clinical situation requires novel PH diagnostic and treatment targets.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary microvascular endothelial cells (HPMVEC), there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induces cell cycle programming, proliferative and anti-apoptotic phenotypes, a process mediated by the activation of E2F Transcription Factor 1 (E2F1) signaling. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH and targeting E2F1 signaling represents a promising approach in PAH patients.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary endothelial cells, there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induced endothelial dysfunctions including upregulation of cell cycle programming and paracrine effect, proliferative and anti-apoptotic phenotypes, impaired cellular junction and BMP signaling. E2F Transcription Factor 1 (E2F1) signaling was showed to mediate the SOX17 deficiency-induced EC dysfunction. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH through E2F1 and targeting E2F1 signaling represents a promising approach in PAH patients.
Project description:Vascular remodeling is the process of structural alteration and cell rearrangement of blood vessels in response to injury and is the cause of many of the world's most afflicted cardiovascular conditions, including pulmonary arterial hypertension(PAH). Many studies have focused on the effects of vascular endothelial cells and smooth muscle cells(SMCs) during vascular remodeling, but pericytes, an indispensable cell population residing largely in capillaries, are ignored in this maladaptive process. Here we report that hypoxia-inducible factor 2α(HIF2α) expression is increased in human PAH patient lung tissues and HIF2α overexpressed pericytes result in greater contractility and an impaired endothelial-pericyte interaction. Using single-cell RNAseq and hypoxia-induced pulmonary hypertension(PH) models, we show HIF2α as a major molecular regulator for pericytes’ transformation into SMC-like cells. HIF2α overexpression in pericyte-selective mice exacerbate PH and right ventricular hypertrophy. Temporal cellular lineage tracing shows that HIF2α overexpressing reporter NG2+ cells (pericyte-selective) relocate from capillaries to arterioles and co-express SMA. This novel insight into the potential role of NG2+ pericytes in pulmonary vascular remodeling via HIF2α signaling suggests a potential drug target for PH.
Project description:Despite recent improvements in management of idiopathic pulmonary arterial hypertension, mortality remains high. Understanding the alterations in the transcriptome–phenotype of the key lung cells involved could provide insight into the drivers of pathogenesis. In this study, we examined differential gene expression of cell types implicated in idiopathic pulmonary arterial hypertension from lung explants of patients with idiopathic pulmonary arterial hypertension compared to control lungs. After tissue digestion, we analyzed all cells from three idiopathic pulmonary arterial hypertension and six control lungs using droplet-based single cell RNA-sequencing. After dimensional reduction by t-stochastic neighbor embedding, we compared the transcriptomes of endothelial cells, pericyte/smooth muscle cells, fibroblasts, and macrophage clusters, examining differential gene expression and pathways implicated by analysis of Gene Ontology Enrichment. We found that endothelial cells and pericyte/smooth muscle cells had the most differentially expressed gene profile compared to other cell types. Top differentially upregulated genes in endothelial cells included novel genes: ROBO4, APCDD1, NDST1, MMRN2, NOTCH4, and DOCK6, as well as previously reported genes: ENG, ORAI2, TFDP1, KDR, AMOTL2, PDGFB, FGFR1, EDN1, and NOTCH1. Several transcription factors were also found to be upregulated in idiopathic pulmonary arterial hypertension endothelial cells including SOX18, STRA13, LYL1, and ELK, which have known roles in regulating endothelial cell phenotype. In particular, SOX18 was implicated through bioinformatics analyses in regulating the idiopathic pulmonary arterial hypertension endothelial cell transcriptome. Furthermore, idiopathic pulmonary arterial hypertension endothelial cells upregulated expression of FAM60A and HDAC7, potentially affecting epigenetic changes in idiopathic pulmonary arterial hypertension endothelial cells. Pericyte/smooth muscle cells expressed genes implicated in regulation of cellular apoptosis and extracellular matrix organization, and several ligands for genes showing increased expression in endothelial cells. In conclusion, our study represents the first detailed look at the transcriptomic landscape across idiopathic pulmonary arterial hypertension lung cells and provides robust insight into alterations that occur in vivo in idiopathic pulmonary arterial hypertension lungs.